Impact printers are known, including the typewriter and various devices used for the printout of computer output data. Such devices normally involve positioning the back surface of a recording member such as a paper web against a backing member and positioning an ink bearing ribbon or the like against the front surface of such recording member. A movable member is then impacted against the rear surface of the ribbon. This movable member may comprise a relief alpha numeric character or the like, or may be a planar surface, in which instance relief alpha numeric characters are contained on the contacting surface of the backing member. In either instance pressure is applied in a pattern form corresponding to the relief pattern, causing pressure transfer of ink from the ribbon to the recording member surface.
A disadvantage of prior art impact printing processes is the transfer member or ink bearing ribbon, which is commonly used in repetitive manner. This results in a progressive loss of print density and in the production of copy of irregular density when the ribbon is partially and irregularly worn. In the past it has been proposed to wet the type face with a liquid ink prior to printing of each character, but while such procedure may be usable for printing of computer output, such methods are not readily adaptable to typewriting, particularly when the typewriter is in irregular use.
The present invention overcomes the disadvantages of the prior art impact printing processes in that it does not use an ink bearing ribbon, nor does it use a liquid ink.